The present invention relates to a rotation control motor, and more precisely, a rotation control motor used as a motor for opening and closing a gull-wing type back door to be opened and closed provided on a vehicle such as an automobile or a sliding door provided on the side or the roof thereof.
A door opening-closing device for opening and closing a sliding door provided on the side of an automobile by a motor is disclosed in JP11-72395A.
For example, as shown in JP10-141409A, a hatch back type automobile or a van is equipped with a gull-wing type back door for taking out and putting in baggage from the rear. A gas spring is provided as opening and closing auxiliary means for assisting opening and closing force of the back door. Generally, the gas spring is filled up with high-pressure gas for supporting the weight of the back door and hydraulic oil for applying damping force near the partition end.
A back door opening-closing device for assisting opening and closing force by a gas spring and a motor is known by JP2004-175211A (see FIG. 9).
However, the back door opening-closing device for assisting opening and closing force by the gas spring contributes little to rotation moment of a gas spring force for rotating the door in a vertical direction because the door and the gas spring are attached approximately in parallel when the back door is closed. Therefore, the door is heavy and is hard to open at the beginning, and jumps up when the door opens at a position in which pressing force overcomes its weight. On the other hand, when the gas spring and the motor are used together, the door can be opened and closed relatively smoothly with the aid of the motor even if the door and the gas spring are attached at the above angle.
However, auxiliary support force by the gas spring or the motor is not usually in proportion to rotation angle of the door. So, when opening torque becomes less on a slope or when the temperature changes greatly, a relationship between rotational position of the door and torque required for rotation differs from expected, which makes the motor high-speed rotation when a motor load is light. After all, the door jumps up forcefully and is likely to collide against an obstacle.
As for the door opening-closing device for opening and closing the sliding door on the side or the roof of the automobile by the motor in a horizontal direction, opening torque of the door differs when the automobile is on the slope. When the door opens downwards, motor load becomes less, the motor rotates at high speed, and the door may open forcefully.